What are the main pre-requisites to implement the principle of \’Res Judicata\’?

The pre-requisite which are necessary to implement the principle of “Res Judicata\” are:

1) There must be a final judgment:

2) The judgment must be on the merits;

3) The issue must be the same in the first and second suits;

4) The parties in the second action must be the same as those in the first, or the successor-in-interest of a party to the prior action.